Terry - The styrofoam bottom is about 3/8" thick, secured to the balsa bottom. I am only assumingthis thickness, I have notpulledit up anywhere. This is a Piedmont ARF. Theoutside of the fuselage, whole plane, covered in Ultra-Cote. My choice would have been MonoKote, not impressed with this covering material. Do it over, I would have ordered an ARC.

Vince